1. Field of the Invention
The invention relates to a gas diffusion layer for a fuel cell, a fuel cell employing this gas diffusion layer, and a method of manufacturing a gas diffusion layer for a fuel cell.
2. Description of Related Art
A fuel cell is equipped with a membrane electrode assembly (an MEA) that is obtained by attaching both electrodes, namely, an anode and a cathode to both faces of an electrolyte membrane (e.g., a solid polymer membrane) having proton conductivity respectively. After both the electrodes of this MEA are supplied with fuel gas and oxidizing gas, for example, hydrogen gas and air via a gas diffusion layer, this fuel cell generates electric power through an electrochemical reaction of hydrogen and oxygen. The gas diffusion layer is required to exhibit gas permeability and electric conductivity. In recent years, various methods of forming the gas diffusion layer from carbon fibers have been proposed (e.g., Japanese Patent Application Publication No. 2009-152128 (JP-2009-152128 A)).
In general, a fuel cell has a stack structure obtained by laminating fuel battery cells having MEA's sandwiched by gas diffusion layers, and is fastened in the lamination direction. This fastening force acts as a load on the MEA's and gas diffusion layers of the fuel cells. In Japanese Patent Application Publication No. 2009-152128 (JP-2009-152128 A), a gas diffusion layer is imparted with elasticity by using ingenuity for the situation of the binding of carbon fibers forming the gas diffusion layer by resin or the diameter of the fibers. Changes in load and dimension in the lamination direction of the cells are absorbed through this elasticity.
Although changes in load and the like are changed through elasticity, the load in the lamination direction of the cells continues to be applied to the gas diffusion layer. Therefore, there is an apprehension that the settling or creeping of the gas diffusion layer may be incurred. Due to this deformation of the gas diffusion layer, it is also feared that a gas flow channel in the gas diffusion layer may narrow.